1. Field of the Invention
The present invention relates to plastic ball grid array (PBGA) packages and more particularly to a die paddle for receiving an integrated circuit die in a plastic substrate thereby providing improved reliability and quality of the packages.
2. Description of the Related Art
An integrated circuit (IC) package is a structure used to electrically connect an IC die (chip) to a printed circuit board (PCB) or other host structure. Each die typically includes input/output (I/O) terminals arranged along a peripheral edge of the die. After the die is mounted on a package, the I/O terminals are electrically connected to bonding pads formed on the package using, for example, wire bond techniques. The package typically includes conductive lines electrically connected to external contacts such as, for example, pins, leads, or solder bumps. When the package is mounted onto a PCB, electrical signals are transmitted between the PCB and the die through these external contacts.
A standard PBGA package includes a plastic substrate having a die paddle thereon and an integrated circuit die mounted on the die paddle. The package further includes inner fingers and outer fingers formed on the upper surface of the plastic substrate.
FIG. 1 is a top view of a plastic substrate 10 having a die paddle 16 comprising of a copper film 12 and a gold ring 14 formed on the peripheral portion of the copper film 12.
FIG. 2 is a top view of a die paddle in the plastic substrate according to the prior art. Via holes 18 through the substrate 10 are formed in an array arrangement. Openings 20 are formed through the copper film 12 and interposed in the via hole array. The outermost via holes 18 and the gold ring 14 are separated by a distance (d0) of about 30 to about 50 mils (1 mil=25.4 μm). A solder resist layer is then formed on the copper film 12 to fill the via holes 18 and the openings 20 so that the copper film 12 can be secured on the plastic substrate.
The outermost via holes 18 or the outermost openings 20 are not limited or restricted by a predetermined distance from the gold ring 14. Therefore, the copper film 12 or the solder resist layer tends to delaminate from the plastic substrate, adversely affecting package quality and reliability.
As a result, there are continuing efforts to further improve substrate and package designs to reduce the probability of delamination.